The field of the invention is synthetically produced higher fatty esters and the present invention is particularly concerned with fatty acid esters produced from internal olefins, carbon monoxide and lower alkanols in the presence of a catalyst containing cobalt.
It is known that by reacting olefins with carbon monoxide and an appropriate compound containing a replaceable hydrogen atom such as water, alkanol and amine in the presence of a catalyst containing a metal of Group VIII of the periodic table of elements and a promoter, fatty acids or the corresponding fatty acid derivatives are prepared as disclosed by J. Falbe in Synthesen mit Kohlenmonoxid (Synthesizing with carbon monoxide), Springer publisher, Berlin, Heidelberg, New York, (1967).
This reaction, known as alkoxycarbonylation, is most of all used to prepare fatty acid esters. In most cases .alpha.-olefins are reacted with lower alkanols having 1 to 8 carbon atoms in the presence of catalysts containing cobalt or nickel. The catalytic systems consisting of a cobalt compound and pyridine or a non-ortho-substituted pyridine derivative are found to be especially active. These systems at the same time are characterized by producing reaction products having high linearity. Furthermore, they extensively suppress the hydroformylation taking place as a side reaction and yield, as is known, aldehydes and acetals as disclosed in U.S. Pat. No. 3,507,891; British Pat. No. 1 269 525 and German Published application Nos. 16 18 156 and 19 63 804, the disclosures of whioh are incorporated herein.
While as a rule the state of the art as disclosed in these U.S., British and German patents do not exclude the use of olefins with internal double bonds, however, the specific examples of these prior art references show that unsatisfactory results are obtained for olefins with internal double bonds when they are reacted under conditions which are favorable to alpha-olefins. Thus, the rate of formation and the linearity of the esters produced from olefins with internal double bonds are strongly decreased, or only inadequate selectivity is achieved.